About the childhood lead exposure data

This page provides general information about the childhood lead exposure data and measures developed by the Minnesota Environmental Public Health Tracking (MN EPHT) Program. For more information about these data, contact MNPH Data Access.

  • The number and percent of children tested for blood lead prior to either 3 or 6 years of age in Minnesota, either by test year - the year that the blood test was performed (annual method) - or by birth year (cohort method) among children tested before 3 years of age.
  • Among children who were tested, the number and percent of children with elevated blood lead levels in the state of Minnesota, by two different methods: birth year (cohort method) and test year (annual method).
  • The geographic distribution of testing rates, elevated blood lead levels, and risk factors for elevated blood lead levels in children, including residing in housing built prior to 1978 (and especially pre-1950 housing), and living in poverty.
  • To inform the public about testing coverage for blood lead levels in children, elevated blood lead levels, and the geographic distribution of associated risk factors for elevated blood levels.
  • For program planning and evaluation by state and local partners.
  • Results are not representative of all children living in Minnesota because blood lead testing is not universal. Statewide, about 80% of children are tested for blood lead by the time they reach 3 years of age, and only about 20% of children under 6 years of age are tested each year. Rates vary substantially across the state as children at higher risk for lead exposure (living in Minneapolis or St. Paul, living in older housing, etc.) are targeted for testing. Learn more about Childhood Blood Lead Screening Guidelines for Minnesota (PDF).
  • Data cannot tell us exactly how or where a child was exposed to lead.
  • Data on blood lead testing and elevated blood lead levels are provided by the MDH Lead & Healthy Homes Program, which implements the Childhood Lead Poisoning Prevention Program (CLPPP), and are extracted from the Blood Lead Information System (BLIS).
  • Data on the geographic distribution of housing age and poverty are taken from the 2014 American Community Survey 5-year estimates.
  • An elevated blood lead level (EBLL) in a child is defined by the CDC and the MDH as a blood test result greater than or equal to 5 micrograms of lead per deciliter of whole blood (mcg/dL) in a child. The reference level was recently lowered from 10 to 5 mcg/dL to identify children with levels much higher than most children.
  • The National Tracking Network defines a “confirmed” elevated blood lead level as one "venous" test result greater than or equal to 5 mcg/dL, or two "capillary" test results greater than or equal to 5 mcg/dL within 12 weeks of each other.
    • Capillary blood specimens are drawn from a finger stick, and the blood is collected either in capillary tubes or on filter paper. These specimens are considered "screening" tests because they are prone to falsely high results because of surface contamination when children's hands are not properly washed (prior to drawing the blood). Capillary tests, however, tend to be more acceptable to parents and may be performed in a wider range of settings (i.e., outside of clinical settings).
    • Venous specimens are considered "diagnostic" tests because they are drawn directly from a vein, but they may be less acceptable to some parents because of a child's discomfort.  These tests also require greater expertise in drawing the blood.
  • Reference levels for lead are based on the U.S. population of children aged 1-5 years who are in the upper 2.5% of children tested for blood lead, based on National Health and Nutrition Examination Study (NHANES) data. Reference levels are expected to decline over time as blood lead levels in U.S. children decline.
  • If a child has multiple confirmed tests, only the highest confirmed test result is displayed. This applies to an individual test year or a birth year. However, children can appear in multiple test years using the annual method. 
  • Blood lead testing is not universal or randomly sampled in Minnesota, so the data collected by the Blood Lead Information System are not representative of all Minnesota children. The MDH Childhood Blood Lead Screening Guidelines direct physicians to order blood lead tests for certain populations at higher risk for lead exposure: 1) children residing in specific geographic areas that have high rates of elevated blood lead levels; and 2) children matching specific demographic groups that tend to have higher rates of elevated blood lead levels.
  • The percent of children tested by birth year in a specific county can occassionally exceed 100%. This is because the percent of children tested is not calculated using the total number of children living in that county but, rather, is calculated using the total number of children born in a county in that birth year as a denominator. The number of children tested prior to 3 years of age in a specific county may be higher than the number of children that were born in that county. 
  • American Community Survey (ACS) data on the proportion of older housing provides a population-based proxy for risk of lead exposure, especially housing built before 1950, because old properties with lead-based paint are the most common source of exposure. However, this measure may not accurately reflect exposure risk for several reasons:
    • ACS data are aggregated to county or census tract areas to provide population-level totals or percentages, so may not accurately reflect exposure risk for individual residents. 
    • Residential addresses in the Blood Lead Information System may not reflect the actual location of a child's exposure.
    • The condition of paint within the home is an important factor in exposure risk, and American Community Survey data does not contain information on housing condition.
    • Older properties that have undergone remediation (e.g., lead hazard removal, enclosure, or encapsulation) may pose less exposure risk.
    • Housing age varies within counties. The percentage of older homes in the county does not determine whether individual children reside in older homes. 
  • Vital statistics data from the MDH Office of the Registrar provide high quality information on all Minnesota births, but errors may occur when using vital statistics data or total births as denominators for the birth cohort lead testing measure. A child's address on a birth certificate, for example, may be different from her/his address at the time of the lead test. Additionally, the number of children born in a specific geographic area does not include children who have moved in or out of that area since birth, so using total births as a denominator may lead to an inaccurate estimation of the number of children tested who are born in a specific year.